Sander drum and floor sanding abrasive sheet



Dec. 27, 1949 N. DEGEN 2,492,849

SANDER DRUM AND FLOOR SANDING ABRASIVE SHEET 2 Sheets-Sheet 1 Filed April 25, 1947 Dec. 27, 1949 N. DEGEN 2,492,849

SANDER DRUM AND FLOOR SANDING ABRASIVE SHEET Filed April 25, 1947 2 Sheets-Shet 2 Patented Dec. 27, 1949 SANDER DRUM AND FLOOR SANDING ABRASIVE SHEET Nicklous Degen, Mason City, Iowa Application April 25, 1947, Serial No. 743,798

7 Claims. (Cl. 51-194) The present invention relates to abrasive apparatus or sanding machines and, more particularly, to floor sanders, of the type employed in conditioning new floors for the reception of finishing materials and for refinishing old, worn floors.

A primary object of the invention is to improve the constructions of the sander drums employed in floor sandingmachines and the like.

Another object of the invention is to provide a sander drum structure having novel means for securing to the surface thereof a sheet, strip or band of flexible coated abrasive material, such as abrasive cloth or paper.

Another important object of the invention is to provide a new and improved coated abrasive sheet, strip or band, adapted to cooperate in an improved manner with the drum of the invention and with drums of other types.

Another object is to provide improvements in sander drums and coated abrasive sheets, cooperating in a novel manner so as to maintain the sheet upon the surface of the drum in the best working condition and to prevent the creation of slack in the sheet which would tend to cause bending, cracking or buckling of the sheet, with consequent shortening of the working life of the abrasive material. To this end, the invention provides means for constantly maintaining the sheet, strip, or band under tension on the surface of the drum.

Another object of the invention is to provide structural features in the drum which facilitate removal of a worn sheet of abrasive material and the replacement thereof by a new sheet.

Another object is to provide a fioor sanding machine having novel means for adjusting and controlling the pressure under which the sander drum is applied to the surface being sanded.

Other and further objects of the invention will be apparent from a consideration of the following description of a" Specific embodiment, shown for purposes of illustration in the accompanying drawings, in which:

Figure l is an elevational view of the sander drum with a coated abrasive sheet mounted upon its surface;

Figure 2 is a longitudinal sectional view through the drum of Figure 1, with certain parts shown in elevation;

the end of the abrasive sheet to the drum;

Figure 5 is a sectional detail on line 55 of Figure 4;

Figure 6 is a fragmentary plan view on an enlarged scale, showing certain details in connection with the means for securing the other end of the abrasive sheet;

Figure 7 is an elevation of the structure shown in Figure 6;

Figure 8 is a plan view of the back side of a coated abrasive sheet, strip, or band in accordance with the present invention, and

Figure 9 is a side elevation of the complete floor sanding machine.

Referring to Figures 1-7, the sander drum preferably comprises a shaft l0, journalled for rotation in ball bearing assemblies I I, I2, carried by the machine casing side walls I 3, l4; spaced drum heads l5, l6 coaxially arranged on the shaft and keyed thereto for rotation therewith; a cylindrical, metallic rim I1 which may be carried by the drum heads and secured thereto by rivets H3 or, in many cases, cast integrally therewith of aluminum or the like; and a resilient outer sleeve IQ of rubber or similar material which may be vulcanized or otherwise secured to the rim l1.

Rotation may be imparted to the drum by a V-belt 20, trained about a pulley 2|, fixed on the end of the shaft l0 and connected to a source of power, as hereinafter described.

The opposite ends of the cylindrical drum are provided with a recess 25 in the rubber sleeve and a notch or opening 26extending through the rim ll axially beyond the drum head It.

The surface of the drum rim I 1, within the recess 25 carries a headed projection 21, about A of an inch from the edge of the rim, over which a strand loop 28 at one end of a rhomboid-shaped abrasive sheet 29 is adapted to be hooked.

The abrasive sheet comprises a backing 30 of paper, cloth, or other flexible sheet material, and a facing layer 3| of abrasive grains, adhesively united to the backing, as is well understood in the art. The acute angle ends or tips of the rhomboid sheet or strip are cut off, as indicated at 32, 33, and cord or other strand Mom 28 and 34 are adhesively united thereto, with the eye portions thereof extending into the general area of the removed tips. The legs of the loops are laid upon the back surface of the abrasive sheet and united thereto by reinforcing tabs 35, 36 under substantial pressure with an interposed body of adhesive.

The abrasive sheet so shaped and produced, and provided with strand loops at its ends, is a new of the present invention.

At the opposite end of the drum adjacent the head [6, there is positioned a lever 40 having a central hub 4| fulcrumed on the shaft I and including diametrically extending arms 42, 43, the latter terminating adjacent the opening 26 and having associated with its end portion a hook or other proj ection 44 about which the other end 100;) 34 of the abrasive sheet may be engaged. The other arm '42 is apertured at 45"for the reception of the hooked end of atension sprin 46, having its other end connected to a hook or other projection 41 carried by the inner surface of the drum rim.

The upper end of th [arm 43 is also provided with a laterally projecting lug or keeper 48 adapted to be engaged by the hooked end 49 of-a latch 59 pivoted upon a pin 51*orthelikecarried by the machine casing I4. The latch is normally urged to the upwardly disposed inoperativeposition by a spring 52 having one end connected t'o'the pin and -the-otherheld between suitable projections 53.

As indicated in-Figures 2 -5, with one end ofthe abrasive sheet 29 held by theifixed projection 21, and the sheet wrapped spirally around the drum rim, the other end loop is engaged with the hook 44(Eig. 3-). The tension'of spring 46 constantly urges the lever and arm 43 in a clockwise direction (Fig. 3), thereby :tendingfurther to wind the sheet on the drum and .to maintain the latter in a taut condition. Whentit'is desired-to relieve the tensionfor rem-ovalzof a band or sheet, the hinged front casing section 55 may beswungupwardly, to give access to the latch :50 so that the latter may. bemanually idepressed, to project the end 49 thereof downwardl into the opening 26 'intoengagementwith 'theilug .or keeper 48 or the arm. 43. With the parts so engaged, the drum may be rotatedin the clockwise direction, reverse to its normal direction of rotation, against the force of spring. 46, to provide slack in the band. This reverse rotation may be readily effected by simply grasping the drum with one hand while "the latch 50 is depressed to *the operative position inengagement with :the'keeper 46-with the other,

in which position the parts will remain because of the hooking engagement between the latch end 49 and the keeper, and the rotational force imparted by the springis. With the slack so provided, the band may be readily removed and a new one placed in "position; with its end looped over the hook "4'4, whereupon the latch may be released and the slack immediately .taken up by the relative forward rotation of the arm 43.

As indicated in Figure '9, the sanding machine may include amain frame 60, upon which an electric driving motor 6fl *iszmounted. The lower casing 500. carries a pair of floor engaging rollers '62 on opposite sides and houses a centrifugal blower 53, provided with 'adischarge conduit 64, leadin to a dust bag or the like, supported by a handle bar '66 which also supports .an electric cable 61 leading from a suitable outlet to the motor 61.

The bl'ower'is connected by an inlet scroll to the area of thesanding drum, as indicatedin Figures Q'an'd 3. Abelt guard 69, carried by'th'e frame in any suitable manner encloses the belt '20, trained about thepulley 2| associated with the drum and about a pulley 10 fast on themotor shaft 'll. The latter carries a second pulley T2 oflarger diameter, connected by a belt 13 to a pulley1'4 on theblower shaft.

A bracket '-'.'5, pivoted atlB to the rear of the -l'ower machine casing iilla isconnected to a caster carria e 11. having a caster' m'swiveled .therein' 4 and including an apertured flange 11', in which a vertically extending rod 19 is loosely received. The lower end of the rod 19 is loosely received in an aperture in the flange and connected thereto by a nut and a spring 8|.

The upper end of the rod I9 projects through an opening in a guiding flange 82 carried by the motor housing and is connected through an adjustable'turnbuckle assembly 84 to a crank arm '85, fast on the lower end of 'a 'rockshaft 86 journalled in bearings 81 carried by the handle bar 66 and connected at its upper end to a rockable handle-88,:horizontally aligned, when in its lowermost position, with the fixed handle 89 at the upper end of the handle bar 66.

When the movable handle 88 is depressed, the crank arm is-swung downwardly, thereby depressing the vertical rod I9 and lowering the caster assembly, by downward swinging movement of the pivoted bracket .15. This action brings the caster wheel 18 .into engagementwith the floor and lifts the1rollers ;fi22from thefioor.

Since the center of gravitylof the entire machine is'positioned only slightlyforwardly of the rollers 62, this actionrwill cause a major portion of the weight of the machine to be transferred to the sander drum, to apply maximum sanding pressure to the floor. By varying the vertical position of the caster 18, the distribution of weight between the caster, the rollersfi? and'the sander drum may be nicely adjusted, to control the effective sanding pressure. When "the caster is in its uppermost position,v the crank arm '85 maybe swung :past dead 'center,.and the machine tipped .rearwardly so that its :entire weight is :supported by the rollers :62'=an'd' the caster Iii, for transporting the :machine, in-inoperative position, from place to place.

It is thought that the structural features 'and mode of operation of the invention. will be entirely clear from the :foregoingdescription. lit :must be understood, however, that the invention is not limited to *thedetails of construction shown and described, but includes 'all .modificationscoming within the scope ofsthe appended claims-and their equivalents.

I claim:

1. A sander :drum for floor sanders and the like comprising aashaft journalled for rotation about its axis, a pair of spaced drum heads coaxial with and fast on the shaft, 'a circumferentially continuous, non-slotted cylindrical rim carried by the 'heads'havingiixed fastening means positioned adjacent one end thereof, for one of a coated abrasive strip adapted to be wound on the rim, a lever fulcrumed intermediate its ends on saidshaft axially beyond the head at the opposite endof the-rim for rotation with the drum and for oscillation with respect thereto and having one end-adjacent the last mentioned end of the rim and its other end spaced therefrom, fastening means for connecting the other end of the strip to the first-mentioned .end of the.lever,.and a tensionspringinterposed.between the other end of the lever andthe inner surface of the rim, axially beyond the adjacent head, tending to urge thelever ln.a direction to tighten the strip on the rim.

2. In a floor sander'or the like, the combination of a casing having bearings associatedtherewith and a sander drum within'the casing comprising a shaft journa-lled in said bearings, a pair of drum heads fixed to'the shaft, a cylindrical rim carried'by the drum'heads, means for securing to the rim; one end of a flexible abrasive band wound around the rim, an arm pivoted on the shaft having a free end, means for attaching the other end of the band to said arm, resilient means urging the arm relative to the drum in a direction to tighten the band on the rim, and normally inoperative means carried by the casing, movable to engage the arm for movement of the drum relative thereto in a direction against the force of said resilient means to slacken the band on the rim to facilitate its release from the arm.

3. In a floor sander or the like, the combination of a casing having bearings associated therewith and a sander drum within the casing comprising a shaft Journalled in said bearings, a pair of drum heads fixed to the shaft, a cylindrical rim carried by the drum heads having a recess at one end and an opening or notch adjacent its opposite end, means disposed in the recess for securing one end of a flexible abrasive band wound around the rim, an arm pivoted on the shaft having its free end adjacent the opening or notch, means for attaching the other end of the band to said arm, resilient means urging the arm relative to the drum in a direction to tighten the band on the rim, a, latch pivoted to the casing at the end adjacent the opening, and means normally maintaining the latch in re tracted position, said latch being manually movable into the opening to engage said arm, whereby the drum may be rotated relative to the arm against the force of said resilient means to slacken the band for removal and replacement of a band.

4. A sander drum for floor sanders and the like comprising a shaft, a pair of spaced drum heads mounted coaxially on the shaft, a cylindrical rim carried by the heads having a fixed projection at one end and an opening at the other, an arm pivoted to the shaft having a free end adjacent the opening and having a projection associated therewith, a diamond-shaped flexible coated abrasive sheet having the tips of its acute angle ends removed and flexible strand loops attached to said ends with eye portions thereof substantially disposed in the removed tip areas, one of said loops being hooked over the projection at the first end and the other being hooked over the projection on said arm with the sheet spirally wound around the drum, and a spring interposed between the arm and the drum tending to pivot the arm relative to the drum in a direction to tension the sheet on the drum.

5. As an article of manufacture, an abrasive sheet of rhomboid shape in plan, having the tips of its acute angle ends removed, a flexible loop at each end having the eye portion thereof substantially disposed in the removed tip area and the free ends lying upon the adjacent back surface of the abrasive sheet and adhesively united thereto.

6. As an article of manufacture, an abrasive sheet, of rhomboid shape in plan, having the tips of its acute angle ends removed, a flexible loop at each end having the eye portion thereof substantially disposed in the removed tip area and the free ends lying upon the adjacent back surface of the abrasive sheet, and a reinforcing layer of sheet material covering said ends and adhesively united thereto and to the adjacent surface of the sheet.

7. A sander drum for floor sanders and the like comprising a shaft journalled for rotation about its axis, a pair of spaced drum heads coaxial with and fast on the shaft, a cylindrical rim carried by the heads and projecting axially therebeyond, said rim having a recess in its outer surface adjacent one end thereof and an opening extending therethrough adjacent the other end beyond the drum head at the last mentioned end, fixed fastening means in the recess below the surface of the rim for one end of a coated abrasive strip adapted to be wound spirally on the rim, a lever fulcrumed on the shaft at the second mentioned end of the rim, inwardly thereof, in axially spaced relation to the adjacent drum head, said lever having diametric arms of substantially equal mass, with the end of one arm positioned in the opening in the rim, means carried by said end of the arm for connecting the same to the other end of such a coated abrasive strip, and a tension spring interposed between the end of the other arm and the inner surface of the rim axially beyond the adjacent drum head, tending to pivot the lever in a direction to tighten the strip on the rim.

NICKLOUS DEGEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 414,115 Kenyon Oct. 29, 1889 714,244 Schmitt Nov. 25, 1902 801,003 Gordon Oct. 3, 1905 906,035 Kraemer et a1. Dec. 8, 1908 1,469,307 Keltie Oct. 2, 1923 1,789,298 Bertrand Jan. 20, 1931 1,904,893 Weidrich' Apr. 18, 1933 2,075,672 Stark Mar. 30, 1937 2,278,564 Reid Apr. 7, 1942 2,399,923 Harris May 7, 1948 

